Your frost dates are the single most important factor in deciding when to plant. The last spring frost tells you when it is safe to transplant warm-season crops outdoors, and the first fall frost tells you when the growing season ends. Everything in your planting calendar flows from these two dates.
How to Find Your Frost Dates
The easiest way is to enter your ZIP code in our free garden planner — it automatically looks up your USDA hardiness zone, last frost date, and first frost date and generates a customized planting calendar. You can also check NOAA historical data or your local cooperative extension office.
Frost Date Reference by Zone
These are averages based on 30-year NOAA climate normals. Your specific microclimate (elevation, urban heat island, proximity to water) may shift dates by 1-2 weeks.
| Zone | Region | Last Frost | First Frost | Season |
|---|---|---|---|---|
| 4a-4b | Upper Midwest (MN, WI, VT) | May 10-25 | Sep 20 - Oct 5 | ~120 days |
| 5a-5b | Central (IA, IL, OH, PA) | Apr 20 - May 10 | Oct 1-15 | ~150 days |
| 6a-6b | Mid-Atlantic (VA, KY, MO) | Apr 10-25 | Oct 10-25 | ~175 days |
| 7a-7b | Southeast (NC, TN, AR) | Mar 25 - Apr 15 | Oct 20 - Nov 5 | ~200 days |
| 8a-8b | Deep South (GA, TX, AZ) | Mar 1-20 | Nov 5-25 | ~240 days |
| 9a-9b | Gulf Coast / SoCal | Feb 1-20 | Nov 25 - Dec 15 | ~280 days |
How Frost Dates Affect Planting
- Warm-season crops (tomatoes, peppers, squash) — transplant outdoors 1-2 weeks after your last frost date.
- Cool-season crops (lettuce, peas, broccoli) — plant outdoors 4-6 weeks before your last frost date. They can handle light frost.
- Indoor seed starting — count backward from your last frost date. See our seed starting guide for crop-by-crop timing.
- Fall planting — count backward from your first frost date to determine the latest safe sowing date for a fall harvest.
Protecting Plants from Late Frost
- Row covers — Floating row cover (frost blanket) adds 4-8 degrees of protection. Drape loosely over plants and anchor the edges.
- Cloches and cold frames — Cover individual plants with milk jugs or glass cloches for overnight protection.
- Water before a freeze — Wet soil holds heat better than dry soil. Water in the afternoon before a frost night.
- Mulch heavily — A thick layer of straw or leaves insulates the root zone.
Automate Your Calendar
Our garden planner builds a Gantt-style planting calendar from your frost dates automatically. Plan your beds with the raised bed guide and maximize space with the spacing chart.